I just read an article on Yahoo News where they talked about seven caves that have recently been discovered on Mars. The researchers believe the caves might be the only places on the planet that would preserve evidence of past or present life. They're talking about microbes.
But I believe (sort of) that Mars was once inhabited by intelligent life. Then their ecosphere was destroyed by some kind of cataclysmic event--nuclear war, global warming? Some of the inhabitants managed to escape to Earth. They may have been our ancestors. They may have interbred with our ancestors. Or they may have passed on some sort of knowledge to our ancestors.
Some of the UFO sightings may be Martians from the past who are visiting Earth in the present. Or they may be the descendants of ancient Martians who live among us.
I've had this theory for a long time. I believe there are secret records hidden in various places on Earth and there may be people in power who are privy to this knowledge.
Or maybe I need to get back on meds.